1. Field of the Invention
The present invention relates to drive mechanisms and more particularly to multi-stage drive mechanisms, for example, multi-stage drive mechanisms for deploying and controlling a control surface, such as a canard.
2. Description of Related Art
A variety of drive systems are known in the art for actuating control surfaces, such as canards, on projectiles, or the like. It is commonly desired to have canards rotate about a deployment axis from within the projectile to deploy the canards, for example after launching of the projectile. Following deployment it is often desired to rotate the canards about an axis different from the deployment axis, for controlling the flight of the projectile.
In the past, mechanisms for canard deployment and control typically require a motor and additional energy sources, such as rotational inertia, springs, gas generators, or the like. A small gear ratio is typically required for a fast canard deployment, but a high gear ratio is required for accuracy when controlling the canard. Typically, the canard is the only item that rotates about the deployment axis, and the canard and its support structure rotate about the control axis. This can result in a complex output shaft and complex support structure due to the slot in the output shaft typically needed to allow the canard to sweep through its deployment angle.
Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for systems and methods that allow for improved performance and reduced cost. There also remains a need in the art for such a drive mechanism system that is easy to make and use. The present invention provides a solution for these problems.